Controlling the amount of fuel and air to be delivered per cylinder for a four stroke internal combustion engine is important to achieve optimum performance. Proper timing of intake and exhaust valves also provide for better performance. Conventional engines include camshafts that regulate the timing of the valves. The rotation of the camshaft can be controlled to ensure proper timing of each valve. In addition cam phasers may be included to alter the position of the camshafts relative to the crankshaft which provides for further opportunities to properly adjust the timing of each valve.
In order to achieve greater engine power, conventional engine valve lift profiles and valve timing designs favor high revolution per minute (RPM) conditions. These designs tend to compromise engine performance at low RPM conditions. This compromise can result in combustion instability at idle, a low RPM condition. Combustion instability may be perceived by a driver as undesirable.